WinCC Communication Manual

Manual 1

This manual is part of the documentation package with the order number:

6AV6392-1CA05-0AB0C79000-G8276-C155-01

Release: September 1999

WinCC, SIMATIC, SINEC, STEP are trademarks of Siemens. The other names used in this manual may be trademarks; their owners rights may be violated if they are used by third parties for their own purposes.

(The transmission and reproduction of this document, and utilization and disclosure of its contents are not permitted unless expressly authorized. Offenders will be liable for damages. All rights, including rights created by patent grant or registration of a utility model or design, are reserved.)

(We have checked the contents of this manual for agreement with the hardware and software described. Since deviations cannot be precluded entirely, we cannot guarantee full agreement. However, the data in this manual are reviewed regularly and any necessary corrections included in subsequent editions. Suggestions for improvements are welcomed.)

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Preface

PrefacePurpose of this ManualThis manual details the planning, installation and startup of a communication connection from WinCC to a PLC. It is organized into the following sections: A general chapter about the topic communication A chapter assisting in selecting the most suitable communication solution A chapter about error diagnostics This manual is available in printed form as well as an electronic online document. The table of contents or the index will quickly point you to the information required. The online document also provides an expanded search function.

Information about SIMATIC Products

Constantly updated information about SIMATIC products can be found in the CA01 catalog. This catalog can be accessed at the following Internet address: http://www.ad.siemens.de/ca01online/ In addition, the SIEMENS Customer Support provides you with current information and downloads. A collection of frequently asked questions is listed at the following Internet address: http://www.ad.siemens.de/support/html_00/index.shtml

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Communication Manual

1 Communication ManualIntroductionThe Communication Manual is part of the WinCC documentation. It details the planning, installation and startup of a communication connection from WinCC to a PLC. The objective of the communication manual is to support the user beginning with the selection of the optimum communication, its configuration and installation, up to the startup. Additionally, the communication manual points the way to a quick solution in case of a problem.

Contents and Structure

The communication manual is organized into four main chapters: General Information ChapterThe first chapter provides the reader with a general overview on the subject of communication, with an emphasis on the communication to WinCC. The necessary technical background knowledge, components used and general configuration steps are detailed. Selection GuideThe second chapter guides the reader through the process of selecting the optimum communication type for his or her application. The general factors that must be considered in making a decision are explained. Diagnosis of the Communication ConnectionThe third chapter contains instructions for locating and correcting errors, should there be problems with the startup of the communication connection. Sample ProjectsThe fourth chapter contains a selection of sample projects with very detailed descriptions pertaining to different communication options. Each sample project details the steps from the installation of the hardware up to the successful startup of the connection.

ConventionsThe communication manual uses the following conventions: Convention Description Denotes an operation using the left mouse button. R D Italic Denotes an operation using the right mouse button. Denotes an operation using a double-click of the left mouse button. Denotes terms of the WinCC environment and terms referring to the elements of the programs interface. Denotes an operating sequence or entry to be followed by the user (color visible only in the online document). Cross references (links) are in blue (color visible only in the online document).

Italic, Green

Blue

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Finding InformationIn the printed version of the communication manual, information can be found in the following ways: The table of contents lists information organized by topic. The index lists information organized by key word. In the online document, information can be found in the following ways: The Contents tab lists information organized by topic. The Index tab lists information organized by key word. The Find tab allows you to search for words in the entire document. The sample projects described in this manual can directly be copied from the online document to your hard disk drive

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2 General Information Chapter

This chapter provides you with a general overview on the subject of communication, with an emphasis on the communication to WinCC. The necessary technical background knowledge, components used and general configuration steps are detailed. This chapter is organized into the following sections: Basics of Communication Communication Networks Communication Configuration

2.1 Basics of Communication

This section of the manual provides you with basic information on the subject of communication. The information presented is universal, i.e. it is not only valid for the communication with WinCC. This section contains information about the following topics: Basic Communication Terms Network Topology Classification of Networks Access Methods ISO-OSI Reference Model Connection of Bus Systems

2.1.1 Basic Communication Terms

This section explains the basic terms pertaining to the subject of communication. It mainly deals with the areas important for the information exchange between a PLC and WinCC. The following explains the most important communication terms, which are used for the information exchange between PLCs and WinCC:

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CommunicationCommunication is the term used to describe the transfer of data between two communication partners. The data transferred can serve different purposes. In the case of the communication between a PLC and WinCC, the data can be used to: Control the communication partner Display the states of the communication partner Report unforeseen states in the communication partner Archive

Communication PartnerCommunication partners are modules capable of communicating with each other, i.e. they can exchange data with each other. They can be central processor boards and communication processors in PLCs or communication processors in PCs.

StationA station is a device that can be connected to one or multiple subnets as a unit. This can be a PLC or PC.

Subnet(work)A subnet is the term used to describe the unit consisting of all physical components necessary to build a data link and the associated data exchange method.

NetworkA network is a unit consisting of one or multiple subnets connected to each other, which can be identical or different. It includes all stations that can communicate with each other.

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ConnectionA connection is a configured logical assignment of two communication partners for the execution of a defined communication service. Each connection has two end points, which contain necessary information for addressing the communication partner and additional properties for establishing the connection.

Communication FunctionsCommunication functions are functions provided by a software interface, which are used by the communication services. Communication functions can transfer data between communication partners having different performance specifications. They can control communication partners or retrieve their current operating state.

Software InterfaceSoftware interfaces provide communication services in end systems. A software interface does not necessarily provide all communication functions of a communication service. A communication service in the respective end system (PLC, PC) can be made available using different software interfaces.

ProtocolA protocol is an exact declaration by bit between the communication partners in order to perform a specified communication service. The protocol defines the content-related structure of the data traffic on the physical line. Among other things, it defines the operating mode, procedure for establishing a connection, data protection and data transfer rate.

2.1.2 Network Topology

This section describes the different structures within a subnet. If multiple, independent automation components are to exchange data with each other, they must be physically connected to each other. This physical connection can be structured differently. Network topology is the basic geometric arrangement of this structure. The individual communication partners form the nodes of this structure.

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Point to PointThis most simple structure is the result of a network that only consists of two communication partners. This arrangement is referred to as a Point to Point connection.

LineA network arrangement in line structure follows a main line, the so-called bus. All communication partners are connected to the bus via feeder lines. Multiple communication partners can not talk simultaneously. Only one communication partner can send at any one time. This necessitates rules that are called bus access methods. These rules are also required for the following structures. The failure of a communication partner has little or no effect on the entire network.

RingIn this structure, the communication partners are connected with each other in such a way that they form a ring. A ring can be composed of sequentially arranged point to point connections. In a network structured like this, each node can act as a repeater. This allows greater distances to be bridged. The failure of a communication partner, however, causes greater problems in the ring structure than in the line structure.

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StarIn a star structure, all communication partners are connected to a central star coupler. This star coupler controls the entire communication. Generally, the failure of the star coupler brings down the entire network. The failure of a communication partner has little or no effect on the entire network.

TreeThe tree structure can be viewed as linked line structures. The line structures can have different dimensions and be of different types. The elements connecting the individual lines are of special importance. If the lines to be connected are of the same type, these elements can be pure repeaters. If the lines to be connected are of different types, converters are necessary.

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2.1.3 Classification of Networks

This section explains the different network classes as pertaining to their geographic size. With regard to geographic size, networks can be classified into three classes. These are: LAN (Local Area Network) : Size < 5 km MAN (Metropolitan Area Network) : Size < 25 km WAN (Wide Area Network) : Size > 25 km An exact classification into one of these classes is sometimes not possible due to uncertain limits.

TopologyBecause the distances to be bridged differ, information is available with regard to the topologies used. The topology of a WAN is dictated by its geographic requirements. In most cases, due to economic reasons, irregularly meshed tree structure networks are the result. The topology of a LAN is more clearly structured, since overall functionality is of greater importance than line economies. Typical topologies for a LAN are line, ring and star.

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2.1.4 Access Methods

This section explains the mechanisms used to regulate how the individual communication partners access the bus. Only one message can be send to the bus at a time. This requires the regulation of when a communication partner can send. In this case, the number of listening recipients is of no importance. The rules determining when a communication partner can send messages are called access methods.

Master SlaveIn the master slave method, the master directs the entire bus traffic. The master sends data to the connected slaves and also prompts them to send data. In most cases, a direct communication among the slaves is not provided. This method distinguishes itself for being a simple and therefore efficient bus controller. The master slave method is also used for field busses. An example for this is the PROFIBUS-DP.

Token PassingIn the token passing method, a token travels through the network signaling the right to transmit. The token is a fixed bit pattern. The owner of the token has the right to transmit. However, he can not hold the token for longer than the previously agreed upon time. The bus access of the masters in the PROFIBUS network is regulated by the token passing method.

CSMA/CDIn the CSMA/CD method (Carrier Sense Multiple Access with Collision Detection), each communication partner can send at any time. However, no other communication partners can send at the same time. Conflict arise, if two communication partners start sending at the same time due to signal delays. In this case, both will detect a collision and stop sending. After a certain time, they will attempt to send again. Industrial Ethernet uses the CSMA/CD method.

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2.1.5 ISO-OSI Reference Model

If the data exchange between two devices is carried out on a shared bus system, it is necessary to define the transmission system and access method. For this reason, the International Standardization Organization (ISO) has defined a 7 layer model. This section deals with this model.

General InformationLayers 1, 2 and 4 are required for a satisfactory and secure communication. Layer 1 defines the physical conditions, e.g. power and voltage levels. Layer 2 defines the access mechanism and the addressing of the communication stations. Layer 4 (transport layer) ensures the data security and consistency. In addition to controlling the transport, the transport layer is also responsible for data flow control, blocking and acknowledgment tasks.

ISO-OSI Reference Model

The layers defined in the ISO-OSI reference model control the behavior of the communication partner. The layers are arranged one on top of the other, with layer 7 being the top layer. Only layers that are alike communicate with each other. How the individual layers are implemented is not defined by the reference model. The implementation depends on the actual case. The individual layers are defined as follows: Layer 7 6 5 4 3 2 1 Name Application Layer Presentation Layer Session Layer Transport Layer Network Layer Data Link Layer Physical Layer Description Makes application-specific communication services available. Converts the data from the standard format of the communication system to the device-specific format. Is responsible for establishing, terminating and monitoring the communication connection. Is responsible for controlling the transport. Is responsible for guiding the data from one address to another. Is primarily responsible for detecting and correcting errors. Defines the bus access method. Defines the physical properties of the data transfer.

Physical LayerThis layer provides for a transparent transmission of the bits via the physical medium. In here, the electrical and mechanical properties as well as the transfer types are defined.

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Data Link Layer

This layer ensures the transfer of bit strings between two systems. This includes the detection and correction of errors or the forwarding of transmission errors as well as the flow control. In local networks, the connection layer also grants exclusive access to the transfer medium. The connection layer is divided into two sub-layers (these sub-layers are also called layer 2a and layer 2b): XE "Data Link Layer" XE "Data Link Layer" Medium Access Control (MAC) Logic Link Control (LLC)

Network LayerThis layer guides the data between two end systems. End systems are the sender and recipient of a message, which might be routed through multiple transit systems. The network layer selects the route.

Transport LayerThe transport layer ensures that a reliable start to end connection is available. The services provided include establishing the transport, transferring the data and terminating the connection. Generally, the user of the service can specify a certain level of quality. Quality parameters include the transfer rate or the undetected error rate.

Session LayerThe primary task of the session layer is to synchronize communication relationships. The session layer services can break down a long transmission into smaller transmissions, i.e. set synchronization points. In case the transmission is terminated before completion, the entire transmission process must not be repeated again (the transmission will resume from a specified synchronization point).

Presentation LayerGenerally, different systems initially talk different languages at the onset of a data exchange. The presentation layer translates the different languages of the communication stations into a uniform language with an abstract syntax.

Application LayerThe application layer includes the application-specific services of the different communication applications. Since a multitude of applications exist, it is especially difficult to come up with uniform standards.

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2.1.6 Connection of Bus Systems

To ensure a continuous flow of information between two different subnets, special connection elements are required. The following section briefly introduces the different types of connection elements.

General InformationDepending on the complexity of the connection or the differences in the subnets to be connected, distinctions can be made between repeaters, bridges, routers or gateways for the network connection. Based on their tasks, these connection elements can be illustrated using the ISO reference model.

RepeaterThe repeater copies the information received from the line to the other side and amplifies it. A repeater is transparent to all layers of the communicating stations, i.e. the physical layer of both networks must be identical. Repeaters are not only used to connect similar subnets, but also to extend an existing subnet (e.g. bus system).

BridgeA bridge is used to connect subnets that work with the same protocols on the data link layer (Logical Link Control LLC). The transfer media and the bus access methods (Medium Access Control MAC) of the connecting subnets can be different. The bridge is primarily used to connect local networks of different topologies. Bridges are also used if special applications require the connection of certain structures to subnets.

RouterThe router connects ISO networks that differ in layers 1 and 2. The router also determines the best communication path for a message through an existing network (routing). Criteria for determining the best path can be path length or smallest transfer delay. In order to perform its tasks, the router changes the target and source addresses of the arriving data packages in the network layer before forwarding them. Since routers have to perform considerably more complex tasks than bridges, their processing rate is slower.

GatewayA gateway connects networks with differing architectures, i.e. any two subnets can be connected. Referring to the ISO reference model, the task of the gateway is to translate the communication protocols of all layers. A gateway also makes the connection of an ISO network to a non-ISO network possible. Network connections via gateways generally require considerably greater effort and offer slower speeds.

2.2.1 Industrial Communication Overview

This section provides you with an industrial communication overview and classifies the different communication types according to their industrial environment.

General InformationDepending on the requirements, different communication networks are available for the industrial communication. The following graphic shows the individual automation levels and their suitable communication networks.

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Management LevelAt the management level, tasks effecting the entire operation are processed. This includes the archiving, processing, evaluating and reporting of process values and messages. The operating data can also be collected and processed from multiple sites - from the management level, other sites can also be accessed. The number of stations in such a network can exceed 1000. Ethernet is the dominant network type at the management level. To bridge greater distances, the TCP/IP protocol is used in most cases.

Cell LevelAt the cell level, the automation tasks are processed. At this level, PLCs, operating and monitoring devices and PCs are connected with each other. Depending on the performance demanded, the dominant network types are the Industrial Ethernet and PROFIBUS.

Field LevelThe field level is the connecting link between the PLCs and the plant. The devices used at the field level supply the process values, messages, etc. and also forward commands to the plant. In most cases, the amounts of data transferred at the field level are small. PROFIBUS is the dominant network type at the field level. To communicate with the field devices, the DP protocol is frequently used.

Actuator-Sensor LevelAt the actuator-sensor level, a master communicates with the actuators and sensors connected to its subnet. A characteristic of this level is the transfer of extremely small data amounts, but with a quick response time.

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2.2.2 Industrial Communication Subnets

This section introduces you to the different subnets used in the industrial communication. Only those subnets relevant for a communication with WinCC will be described. An explanation of the AS-i (Actuator-Sensor Interface) will therefore be omitted.

General InformationDepending on the requirements, different subnets are available for the industrial communication. The following lists the different subnets by increasing order of performance: MPI PROFIBUS Industrial Ethernet

MPIMPI (Multi Point Interface) is suitable for small size networks at the field and cell level. It can only be used in conjunction with the SIMATIC S7. The MPI subnet uses the MPI interface of the PLCs central processor card for the communication. This interface has been designed as a programming interface and quickly reaches its performance limits with increasing communication demands. A PC can access an MPI subnet via an installed MPI card. Communication processors providing access to the PROFIBUS can also be used.

PROFIBUSThe PROFIBUS (Process Field Bus) is a subnet designed for the cell and field level. It is an open, manufacturer-independent communication system. PROFIBUS is used to transfer small to medium sized data amounts between few communication partners. With the DP (Decentralized Periphery) protocol, PROFIBUS is used for the communication to intelligent field devices. This type of communication is characterized by quick, cyclic data transfers.

Industrial EthernetThe Industrial Ethernet is a subnet suitable for the management and cell level. It is used to transfer large amounts of data over long distances between a large number of stations. The Industrial Ethernet is the most powerful subnet available for the industrial communication. It can be configured and expanded easily without great effort.

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2.2.3 Industrial Communication via MPI

This section introduces you to the MPI subnet. It describes its properties, applications and components used.

General InformationThe MPI subnet can be used at the cell and field level. The communication partners to be linked must be members of the SIMATIC S7 family. The MPI subnet can economically link a small number of stations. However, the lower performance of an MPI solution must be acceptable. The maximum number of stations is limited to 32. MPI uses the available MPI interface of the SIMATIC S7 family PLCs for the communication. This interface has been designed as a programming interface. The following graphic shows an example of an MPI network. The bus access of the individual communication stations is realized via the programming interface of the corresponding central processor card.

Access MethodMPI uses the token passing access method. The right to access the bus is forwarded from station to station. This access right is called a token. If a station receives the token, it has the right to send messages. If the station has no messages to send, it forwards the token directly to next station in the logical ring. Otherwise the token will be forwarded after a specified hold time.

Transfer MediaThe same transfer method used for a PROFIBUS network can be used for an MPI network. It can be designed as an optical or electrical network. The transfer rate generally used is 187.5 kBit/s. However, the latest versions of the S7-400 can achieve transfer rates of up to 12 MBit/s.

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2.2.4 Industrial Communication via PROFIBUS

This section introduces you to the PROFIBUS subnet. It describes its properties, applications and components used.

General InformationThe PROFIBUS is a subnet designed for the cell and field level with only a limited number of stations. The maximum number of stations is 127. PROFIBUS is an open, manufacturer-independent communication system. It is based on the European Standard EN 50170, Volume 2, PROFIBUS. By meeting these requirements, PROFIBUS guarantees openness for the connection of third-party components conforming to this standard. The following graphic shows a PROFIBUS network. It illustrates the components used by the individual communication partners to realize their bus access. The openness of the PROFIBUS concept of course permits the connection of third-party devices to the communication network.

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2.2.4.1 The PROFIBUS Access Method

A PROFIBUS network distinguishes between active and passive network stations. Active stations use the token passing access method, whereas passive stations use the master slave access method. Because of this, the PROFIBUS access method is also called Token Passing with subordinated Master Slave.

All active stations, following a set sequence, form a logical ring. Each active station knows the other active stations and their sequence on the PROFIBUS. The sequence is independent of the physical station arrangement on the bus. The bus access right is passed from active station to active station. This access right is called a token. If a station receives the token, it has the right to send messages. If the station has no messages to send, it forwards the token directly to next station in the logical ring. Otherwise the token will be forwarded after a specified hold time. If an active station possessing subordinated passive stations receives the token, it will query its passive stations and send data to them. Passive stations themselves never receive the token.

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2.2.4.2 PROFIBUS Protocol Architecture

PROFIBUS protocols optimized for different applications are available. The following lists the three available protocol versions: PROFIBUS-FMS (Fieldbus Message Specification) is suitable for the communication of PLCs in smaller cell networks and for the communication to field devices with FMS interfaces. The powerful FMS services offer a broad application scope and great flexibility for the management of extensive communication tasks. PROFIBUS-DP (Decentralized Periphery) is suitable for the connection of decentralized peripheral devices, such as the ET 200, with very fast response times. PROFIBUS-PA (Process Automation) has been designed specifically for process engineering and is a communication-compatible expansion of PROFIBUS-DP. It allows the connection of field devices in areas potentially threatened by explosions. All protocols use the same transfer technology and uniform bus access protocol - they can therefore all be operated on the same line. In addition to the above protocols, the following communication options are supported: Via FDL services (SEND/RECEIVE), the communication to any communication partner supporting FDL (Field Data Link) can be quickly and easily implemented. S7 functions allow the implementation of an optimized communication within the SIMATIC S7 family.

2.2.4.3 Transfer Media

A PROFIBUS network can be designed as an optical or electrical network. Mixed structures, consisting of optical and electrical PROFIBUS networks, can also be implemented.

Electrical NetworkAn electrical PROFIBUS network uses a shielded, twisted, two-wire cable as its transfer medium. The RS 485 interface operates with voltage differences. It is therefore less susceptible to interference than a voltage or current interface. The various PROFIBUS stations are connected to the bus via a bus terminal or bus connector plug. A maximum of 32 stations can be connected to each segment. The individual segments are connected to each other via repeaters. The transfer rate can be set in steps from 9.6 kBit/s to 12 MBit/s. The maximum segment length is determined by the transfer rate. The following table lists transfer rates and their respective maximum distances. The distances listed are either with or without the use of repeaters. Transfer Rate 9.6 - 93.75 kBit/s 187.5 kBit/s 500 kBit/s 1.5 MBit/s 3 - 12 MBit/s Size without Repeaters 1000 m 800 m 400 m 200 m 100 m Size with Repeaters 10 km 8 km 4 km 2 km 1 km

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Optical NetworksAn optical PROFIBUS network uses fiber optic cables as its transfer medium. Optical networks are not susceptible to electromagnetic interference, suitable for long distances and use either plastic or glass fiber optic cables. The transfer rate can be set in steps from 9.6 kBit/s to 12 MBit/s. The maximum segment length is independent of the transfer rate, with the exception of redundant optical rings. Two connection methods are available to build an optical PROFIBUS network: Optical Link Modules (OLM) using plastic or glass fiber optic cables. OLM allows the configuration of an optical network in a line, ring or star structure. End devices are connected directly to the OLM. Optical rings can use single fiber cables (costoptimized) or dual fiber cables (increased network availability). Optical Link Plugs (OLP) allows passive bus stations to be connected to an optical single fiber cable ring. The OLP is inserted directly into the PROFIBUS interface of the bus station. In an optical PROFIBUS network, the maximum distance for all transfer rates is greater than 100 km.

2.2.5 Industrial Communication via Ethernet

This section introduces you to the Industrial Ethernet subnet. It describes its properties, applications and components used.

General InformationThe Industrial Ethernet is the most powerful subnet in the industrial environment. It is suitable for the management level as well as for the cell level. Industrial Ethernet makes the transfer of large data amounts over great distances between a large number of stations possible. Industrial Ethernet is an open communication network following the IEEE 802.3 standard. It has been specifically designed to economically solve demanding communication tasks in the industrial environment. The major advantages of this subnet are its speed, simple expandability and openness as well as its high availability and global distribution. The configuration of an Industrial Ethernet subnet requires only small efforts.

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Access MethodThe Industrial Ethernet uses the CSMA/CD (Carrier Sense Multiple Access/Collision Detection) access method. Before sending a message, each communication station must check if the bus line is clear. If the bus line is clear, the station can send the message right away. If two communication stations start sending messages at the same time, a collision will occur. This collision is detected by both stations and they will stop sending. After a randomly selected waiting period, they will attempt to send again.

2.2.5.1 Industrial Ethernet Protocol Profiles

Communication via the Industrial Ethernet can be performed using one of the following protocol profiles: MAP (Manufacturing Automation Protocol) uses the MMS services of the user interface. The TF protocol contains the open SINEC AP automation protocol that has proven itself in many applications. Based on it, technological functions are available. SEND/RECEIVE provides functions which allow a quick implementation of the communication between S5, S7 and PC. S7 functions provide optimized communication within the SIMATIC S7 family. Communication profiles can be changed without changes to the application programs.

2.2.5.2 Transport Protocols

For the communication via the Industrial Ethernet, the following transport protocols are available: The ISO transport provides services for the transfer of data using the connections. Active data can be blocked into multiple data messages. The ISO-on-TCP transport corresponds to the TCP/IP standard with the RFC 1006 expansion. This expansion is required, since TCP/IP uses the data stream communication which does not block data. UDP can only perform unsecured data transfers.

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2.2.5.3 Transfer Media

An Industrial Ethernet network can be designed as an optical or electrical network. Mixed structures, consisting of optical and electrical networks, can also be implemented. This allows you to take advantage of the configuration options of both network types.

Electrical NetworkAn electrical Industrial Ethernet network can be designed using two different cabling types: The triaxial cable (AUI) or the Industrial Twisted Pair cable (ITP). To connect communication modules possessing only AUI interfaces to an ITP network, a twisted pair transceiver (TPTR) must be used.

Optical NetworkAn optical network can be designed as a line, ring or star structure. As the transfer medium, glass fiber optic cables are used exclusively.

2.2.6 OPC Interface Standard

This section introduces you to the new interface standard OPC and describes the applications of this concept.

General InformationOPC (OLE for Process Control) is a new communication standard for components in the automation field. This concept integrates office applications, HMI systems such as WinCC, PLCs and field devices. OPC is defined as an open interface standard by the OPC Foundation, whose members include more than 120 companies from the automation sector. The current OPC specifications can be viewed via the Internet. The site also contains information about the individual OPC Foundation members and their product spectrum. The Internet address of the OPC Foundation is: http://www.opcfoundation.org

Communication ConceptMinimum components of an OPC configuration always include an OPC server and an OPC client. The OPC server is an application that makes data available to an OPC client, who retrieves this data and further processes it.

WinCC and OPC

WinCC can communicate as an OPC client with any PLC, for which a corresponding OPC server is available. Among others, several SIMATIC NET OPC servers are available. WinCC also has an OPC server. This allows data exchanges with other applications possessing an OPC client interface (which also includes WinCC).

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2.3 Communication Configuration

This section of the manual contains information about the configuration of a communication connection in a WinCC project. It will illustrate the general concept of the WinCC process communication, its configuration and diagnosis. The following topics will be discussed: WinCC Process Communication WinCC Communication Configuration

2.3.1 WinCC Process Communication

Data ManagerThe WinCC Data Manager manages the database. This data manager is not visible to the user. The data manager works with the data generated by the WinCC project and stored in the project database. It manages the WinCC tags during runtime. All applications of WinCC must request data from the data manager in the form of WinCC tags. These applications include Graphics Runtime, Alarm Logging Runtime and Tag Logging Runtime.

Communication DriversIn order for WinCC to communicate with different types of PLCs, communication drivers are utilized. The WinCC communication drivers connect the data manager to the PLC. A communication driver consists of a C++ DLL, which communicates with the data managers interface - the so-called Channel API. The communication driver supplies the WinCC tags with process values.

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Communication StructureThe WinCC data manager manages the WinCC tags in runtime. The various WinCC applications request tag values from the data manager. The data managers task is to fetch the requested tag values from the process. It accomplishes this via the communication driver integrated into the WinCC project. The communication driver forms the interface between WinCC and the process using its channel units. In most cases, the hardware-based connection to the process is implemented using a communication processor. The WinCC communication driver uses the communication processor to send request messages to the PLC. The communication processor then sends the requested process values in corresponding answer messages back to WinCC.

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2.3.2 WinCC Communication Configuration

This section describes the configuration steps necessary in WinCC to establish a communication connection to a PLC.

Communication DriversThe communication in WinCC is performed using various communication drivers. A number of communication drivers are available for the connection of different PLCs on different bus systems. A communication driver is added to a WinCC project in the WinCC Explorer. In there, the communication driver is added to Tag Management. Generally, this is performed via a R on the Tag Management entry and the selection of Add New Driver from the pop-up menu. This action will display all communication drivers installed on the computer in a dialog box. Each communication driver can only be added once to a WinCC project.

Communication drivers are files with the extension .chn. The communication drivers installed on the computer are located in the Bin subfolder of the WinCC installation folder. After the communication driver has been added to the WinCC project, it will be listed in the WinCC Explorer, as a sub-entry next to Internal Tags, under Tag Management.

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Channel UnitThe communication driver entry in Tag Management contains at least one sub-entry. This is the communication drivers so-called channel unit. Each channel unit forms the interface to exactly one subordinated hardware driver and thus to the PCs communication module. The communication module addressed by the channel unit must be defined. This communication module is assigned in the System Parameters dialog box. This dialog box is opened by 8R on the corresponding channel unit entry and selecting System Parameters from the pop-up menu

This dialog boxs appearance depends on the selected communication driver. Generally, the module to be used by the channel unit is specified in here. However, it might also be necessary to specify additional communication parameters.

ConnectionFor a channel unit to read and write process values of a PLC, a connection must be set up to this PLC. A new connection is set up by R on the corresponding channel unit entry and selecting New Driver Connection from the pop-up menu. The connection parameters to be set depend on the selected communication driver. The connection must always be assigned a name unique to the project. The additional parameters generally specify the communication partner to be reached.

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General Information Chapter

WinCC TagsTo gain access to certain data in a PLC, WinCC tags must be configured. These are also referred to as external tags as opposed to internal tags, which do not possess process driver connections. WinCC tags must be created for each configured connection. To create a new WinCC tag, R on the corresponding connection entry and select New Tag from the pop-up menu.

The Tag Properties dialog box will be opened, in which different properties of the tag are defined. The tag must be assigned a name unique to the WinCC project. Additionally, the data type of the tag must be specified. WinCC supports the following external tag data types: Binary Tag Unsigned 8-Bit Value Signed 8-Bit Value Unsigned 16-Bit Value Signed 16-Bit Value Unsigned 32-Bit Value Signed 32-Bit Value Floating-Point Number 32-Bit IEEE 754 Floating-Point Number 64-Bit IEEE 754 Text Tag 8-Bit Character Set Text Tag 16-Bit Character Set Raw Data Type For numerical data types, with the exception of the Binary Tag data type, there is the option to perform a Format Adaptation. This means that the WinCC tag can refer to a data area in the PLC, which does not correspond to the data type of the WinCC tag. By default, the Adapt Format option is not active. The WinCC tag is then assigned a data area in the PLC, which corresponds to the data type of the WinCC tag.

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Also, for numerical data types, with the exception of the Binary Tag data type, a Linear Scaling can be performed. This means that the value range of a process value will be mapped linearly to a defined value range of a WinCC tag. For example, the process can request an entered set-point value in the unit bar, whereas the value is entered in WinCC by the user in the unit mbar. The easiest solution for such a problem is the application of a liner format adaptation, as illustrated in the following graphic.

Tags of the data type Text Tag 8-Bit Character Set and Text Tag 16-Bit Character Set require a length specification. This length is specified in characters. This means that a tag of the Text Tag 16-Bit Character Set data type, which is to receive 10 characters, must be configured with a length of 10. WinCC tags must be allocated a data area in the communication partner. The tags must be addressed in a certain way in the communication partner. The addressing type depends on the type of communication partner. The dialog box for specifying a tag address can be opened via the Select button.

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Selection Guide

3 Selection GuideThis chapter helps you in selecting the right communication solution for your application. It outlines a general procedure for selecting the most suitable communication solution for a project based on the existing conditions and requirements. The factors influencing the decision for a communication solution are complex. The stage (time) at which the decision is made, is of major importance. The best time to make a decision is at the planning stage of a plant. Should the plant already exist, the room available for making a decision is more restricted because of the existing conditions. Based on the experiences in a number of projects, the following can be said: The budget for a communication solution should always include reserves of approximately 20 percent. This comparably small additional cost can generally be recuperated in savings realized in the later configuration and expansion stages of the communication solution. The main factors that enter into the decision making process for a certain communication solution include the amount of data to be transferred, the number of connected stations, the network size and its expandability. This chapter is organized into the following sections: Project AnalysisExact specification of the communication demands made in your project. Performance DataComparison of the performance of the different communication solutions and how they meet the required demands.

3.1 Project Analysis

This section provides you with a guideline, which helps you specify the project requirements made to the communication system. To select the correct communication solution, it is important to know what requirements need to be met. This means that all necessary data has to be collected and analyzed. All following information cover the subject of determining project requirements made to the communication. An important base for defining your own requirements is the Specifications framework. In addition, the specifications of already existing hardware and software must be considered. This chapter is organized into the following sections: SpecificationsDetermine the amounts of data to be processed and the origin of the data. Configuration NotesReduce the communication load and the increase the performance through supporting configurations.

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3.1.1 SpecificationsThe specifications framework helps determine the amount of data that has to be processed by the communication system. This includes determining the amount of data required by the WinCC project. Also, it must be determined from which locations the WinCC project is collecting this data. To assess the amount of data required by the WinCC project, simply add up of the amounts of data required by the individual applications per time unit. In detail, this means the determination of the requirements made to the communication system by: Graphics Runtime Alarm Logging Runtime Tag Logging Runtime Global Script Runtime (also of C actions in individual WinCC screens) Customer-specific applications

Requirements of Graphics Runtime

Graphics Runtime only requests the data from the data manager needed to update the values of the currently displayed WinCC screen. This means that the requirements made to the communication system can vary from screen to screen. The screen with the highest communication volume should enter into your decision for a Graphics Runtime communication system.

Requirements of Alarm Logging Runtime

Alarm Logging Runtime request all tags to be monitored, in a cycle defined by the system, from the data manager. This can be event tags or tags for monitoring limit values. If Alarm Logging has not been configured yet, the data for determining the number of messages can be deduced from measurement point and I/O lists.

Requirements of Tag Logging Runtime

Tag Logging Runtime requests all tags to be archived (using the specified update cycle) from the data manager. The display of these archived tag values - trend or table - has no effect on the requirements made to the communication system. If Tag Logging has not been configured yet, the data for determining the number of tags (whose values are going to be archived) can be deduced from the customer requirements for archiving and reporting processes.

Requirements of Global Script Runtime

The requirements made by Global Script Runtime to the communication system depend on the type of tag request in the WinCC scripts and their execution cycle. Additionally, consider that there are WinCC scripts executed globally and WinCC scripts executed locally (in various WinCC screens). The determination of the requirements made by Global Script Runtime to the communication system is in most cases only a rough estimate of the amount of data to be processed in the worst case.

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Communication Messages The communication between the individual communication partners is carried out by sending messages. This includes the communication between PLCs and HMI stations PLCs themselves PLCs and their peripheral devices Instead of the term message, the term PDU (Protocol Data Unit) is also often used. For example, a WinCC station requests data from a PLC by sending a request message. The PLC will then send the requested data to the WinCC station in a return message. The following graphic shows the structure of a message:

Note that certain data types permit the configuration of a format adaptation. In this case, the net space requirement in the communication system corresponds to the space occupied by the WinCC tags adapted format, not its original format. Example of a format adaptation: A WinCC tag of the Unsigned 32-Bit Value data type is only mapped using 16 Bits in the memory area of the PLC. This is carried out using the DwordToUnsignedWord adapt format. The space requirement of the WinCC tag in the communication message will no longer correspond to the value of 4 Bytes listed in the table above, but to only 2 Bytes.

Gross Space Requirement of the WinCC Tags

To transfer a tag in a message from one communication partner to another, not only the net data is relevant. In addition, address information for the assignment of the individual tags in the communication partner is required. For example, this additional information requires 4 Bytes per tag for the SIMATIC S7 communication. This can significantly increase the space requirements for the individual tags. Among other things, the space requirement of a tag with a net space requirement of 1 Byte increases by a factor of five because of the additionally transferred information. These numbers are specific to the communication with the SIMATIC S7, however, similar numbers can be expected using different communication systems.

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Update CycleAn update cycle must be specified for all WinCC tags, whether they are requested by Graphics Runtime, Alarm Logging Runtime or any other application. This update cycle greatly influences the requirements made by the WinCC project to the communication system. The update cycles should therefore be selected very carefully. In connection with WinCC, the update cycles listed in the following table are generally used. Additionally, a maximum of 5 user-defined cycle times can be set. To determine the data traffic caused by WinCC, a table using the template below could be devised. In this table, the amounts of data required by the various applications are entered in Bytes. Update Cycle Upon Change 250 ms 500 ms 1s 2s 5s 10 s 1 min 5 min 10 min 1h Used-Defined Cycle 1 Used-Defined Cycle 2 Used-Defined Cycle 3 Used-Defined Cycle 4 Used-Defined Cycle 5 For the communication system, the update cycle Upon Change means that the tag is requested in a cycle of 250 ms. Graphics RT Alarm Lg. RT Tag Lg. RT Global Sc. RT

Determining the Aggregate Data Volume

The amounts of data determined for the individual applications must now be added together. This results in the total communication load caused by WinCC. Note: The method used in this section to determine the requirements made by WinCC to the communication system are not exact to the Byte. Rather, it is an estimation of the data throughput that the communication system will encounter during plant operation.

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Determining the Number of Messages

After the data volume to be processed per application and the time unit has been determined, an approximation of the number of messages needed could be made. This approximation also requires the maximum message length to be known, which is specific to a communication solution. The maximum message length varies greatly depending on the communication network and communication modules used. However, the number of messages for different communication solutions can be determined. Even if these numbers are most likely not exact, they still help in making a decision. Several factors must be considered in determining the approximate number of messages per time unit. One of these factors is the number of communication partners, from which data is requested. Also, the type and manner in which a communication partner answers requests must be considered. For example, the SIMATIC S5 uses one message for each data block, whereas the SIMATIC S7 is capable of grouping multiple data blocks into one message.

Limitations on the Number of Messages

In most cases, a PLC is connected to the communication system via a communication processor. Such a communication processor can only process a certain number of messages per time unit. This value generally lies between 15 and 20 message per second. A defining property of a communication system is its transfer rate. This value allows the approximation of the number of messages of a certain length, which can be processed per time unit. The higher the transfer rate, the higher the maximum number of possible communication messages per time unit.

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Considering additional Communication Stations

In addition to the requirements made by WinCC to the communication system, other factors impact the decision for a certain communication solution. This section explores these factors in greater detail. The following points must be considered in making a decision for a certain communication solution: The communication between the individual PLCs. The communication between the PLCs and connected field devices. The communication of other WinCC stations. The communication of other connected stations (operator panels, tele-service stations and such). Stated more simply, the number of additional stations participating in the communication must be considered.

3.1.2 Configuration Notes

The type of configuration has a major impact on the requirements made by WinCC to the communication system. The user can - by following some basic guidelines - configure a good performing and easily expandable communication system. This section explains how some options can minimize the required load on the communication system already in the planning stage. The user should be aware what effects different configurations have on the communication system. The advantages of a configuration that has been coordinated with the communication system include greater performance of the end product and greater flexibility with later expansions. This will result in greater customer satisfaction and reduced costs (for the current project and also for later expansions).

3.1.2.1 Data Update Cycle

Well selected update cycles in a configuration have a major impact on the performance of a communication system. When determining the update cycles, always consider the system as a whole: From a technical point of view, determine what kind of values are being processed and how often new values should reasonably be requested from the PLC. For example, the following could be considered in making a selection for an update cycle: Is it a major disadvantage for a plant operator, if he is notified about a 1 Celsius change in temperature 10 seconds after the actual event occurs instead of after 250 milliseconds? Is it necessary to archive to temperature progress of a tank measuring 5000 liters in 500 millisecond cycles? By selecting update cycles matched to the process, the quantity of data can be significantly reduced in most cases. Request messages group tags that have the same update cycle, i.e. if a lot of different update cycles are used, the total number of messages increases, which negatively impacts the performance of the communication system.

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3.1.2.2 Data Update Type

The WinCC data managers task is to supply the various applications of the WinCC project with process data. For this purpose, the data manager must update its database at the requested cycles. How the data manager updates the database influences the load on the communication system.

Active WinCC Station

There are several possibilities of how the required data can be updated. If the WinCC station is appearing as an active partner, the update can be performed by so-called acyclic or cyclic read services.

The acyclic read service requires two communication messages for each update. The WinCC station sends a request to the PLC, which then processes it using a reply message (or multiple reply messages). If the cyclic read services is used, the WinCC station registers a read request at the PLC, which then processes it during the corresponding cycle. If the data is no longer needed or its content changes, the WinCC station will cancel the corresponding request.

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Active PLCIn this data update variation, the PLC is actively sending data to WinCC, if it recognizes a change of data. This reduces the data traffic to a minimum, however, the configuration of the PLC becomes more complex.

Configuration GuidelineIn general, a meaningful combination of both data update types described is the most costeffective configuration approach.

3.1.2.3 Data Organization

The organization of the data present in the PLC can have a significant influence on the communication load. This depends greatly on the type of PLC used.

Grouping Data Areas

SIMATIC S5 systems group the requested data into datablocks. The larger the degree of scattering of the required data in the PLC, the larger the number of required messages. It is recommended to have the communication-relevant data contained in 3 to 5 datablocks in the PLC. If a scattering of data cannot be avoided, it can still be advantageous to locate the scattered data in the same data area. However, weigh the advantages attained for the communication system with the disadvantages created for the PLC.

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Optimizing MessagesSIMATIC S7 systems are capable of packaging even scattered data into one communication message. However, grouping communication-relevant data into a few datablocks can still provide advantages. The PLC is capable of performing an optimization of the message structure. This results in the transfer of more requested user data via one message. In general, for each requested tag, its address information must be transferred in addition to its process value (net data). If tags are located in neighboring or adjacent data areas, the required address information can be reduced.

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3.2 Performance Data

This section contains detailed information about the performance of the various communication sytems and their strengths and weaknesses. The first part compares the differing communication systems. This is followed by detailed performance data about the individual communication systems and information about the communication options WinCC has for using this system. This allows the user to select the best communication solution for the requirements determined in the previous chapter. The decision for a communication solution involves the selection of an available communication system and the hardware to be used.

3.2.1 Comparison of Communication Systems

To make a decision for a certain communication system, you need to know the performance capabilities of the available communication options. The following makes a comparison of the individual communication systems. The criteria used to measure the performance of the individual communication systems are, among others: the transfer rate the number of stations the message length the network dimension the possible communication partners the costs

Comments: The correct name of the entries in the communication driver column starting with S5 includes the prefix SIMATIC. The entries in the communication driver column starting with S7 correspond to the various channel units of the SIMATIC S7 PROTOCOL SUITE.

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Cost FactorThe greater the demands on a communication system, the higher the cost of implementation. The following diagram illustrates the relationship of a communication system to its expected implementation cost.

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3.2.2 Serial Communication

The most cost-effective option to communicate from WinCC to a PLC is the formation of a serial communication connection. The COM interface of a WinCC station is used for the communication module.

Communication Partner Two WinCC communication drivers are available for establishing a serial communication connection to the SIMATIC S5 product line. SIMATIC S5 PROGRAMMERS PORT AS511Communication via the programming interface of the respective CPU. SIMATIC S5 SERIAL 3964RCommunication via the serial interfaces The following graphic illustrates the PLCs that can be addressed with each communication driver.

Communication DataEach COM interface of the WinCC station can address a maximum of one PLC. The total number of addressable PLCs can be looked up in the following table. The enclosed values represent the recommended maximum number. Communication Driver SIMATIC S5 PROGRAMMERS PORT AS511 SIMATIC S5 SERIAL 3964R PLC 4 (2) 2

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3.2.3 Communication via MPI

3.2.3.1 Communication ProcessorsTo implement a communication connection to an MPI network, the WinCC station must be equipped with a suitable communication processor. The same communication processors can be used that are used for the connection to the PROFIBUS network. Additional information can be found in the Communication Processors section of the PROFIBUS description. The following table contains the communication processors available for the connection of a WinCC station to the MPI network and the driver software to be used. Communication Processor CP 5412 A2 CP 5613 CP 5511 CP 5611 Configuration/Type ISA Card/Hardnet PCI Card/Hardnet PCMCIA Card/Softnet PCI Card/Softnet Driver Software PB S7-5412 PB S7-5613 S7-DOS S7-DOS

Comment: The S7-DOS software is included in the delivery scope of WinCC.

3.2.3.2 SIMATIC S7 PROTOCOL SUITE

The SIMATIC S7 PROTOCOL SUITE communication driver provides the communication to SIMATIC S7-300 and S7-400 PLCs using various channel units. Among others, an MPI channel unit for the communication via MPI is available.

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Communication DataThe MPI channel unit supports the communication via Hardnet and Softnet modules. Per PC, only one module for the MPI communication can be used. The following table lists the number of PLCs that can be addressed by each communication processor used in the WinCC station. The enclosed values represent the recommended maximum number. Communication Processor Hardnet Module Softnet Module Communication Connections 29 (6) 29 (4)

3.2.4 Communication via PROFIBUS

3.2.4.1 Communication ProcessorsTo implement a communication connection to a PROFIBUS network, the WinCC station must be equipped with a suitable communication processor. In addition, suitable driver software must be installed for the desired communication protocol. Two types of communication processors are available for WinCC. These are communication processors for the so-called Hardnet and Softnet. The main difference between these two is that Hardnet modules have their own microprocessors to reduce the loads on the computer's CPU and Softnet modules do not. XE "PROFIBUS" Hardnet The entire protocol software runs on the module. The simultaneous operation of two protocols is possible (multi-protocol operation). Module is more powerful than a Softnet module. Softnet The entire protocol software runs on the computer's CPU. Only one protocol can be operated at a time (single-protocol operation). Module costs less than a Hardnet module. The following table lists the available communication processors for the system connection to a WinCC station. Communication Processor CP 5412 A2 CP 5613 CP 5511 CP 5611 Configuration ISA Card PCI Card PCMCIA Card PCI Card Type Hardnet Hardnet Softnet Softnet

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3.2.4.2 Communication Drivers

In WinCC, several communication drivers for the communication via PROFIBUS are available.

Comments: The number of available channel units listed in the table equals the number of communication processors that can be operated by the communication driver in the WinCC station. The maximum number of stations in a PROFIBUS network is 127 (with repeaters).

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3.2.4.3 PROFIBUS DPVia the communication driver PROFIBUS DP, a WinCC station can communicate with all PLCs and field devices that can be operated as DP slaves. The application of the communication driver PROFIBUS DP in WinCC makes sense, if there is communication to a large number of subordinated devices with only a small data volume. A very fast tag update can be achieved despite scattered data. The communication runs via the cyclic data exchange of PROFIBUS DP, where the WinCC Station acts as the DP Master.

Communication PartnerVia the communication driver PROFIBUS DP, communication can be established to all PLCs and field devices that can be operated as DP slaves. The following graphic illustrates the possible communication partners.

Communication DataThe communication driver PROFIBUS DP exclusively supports the communication via the communication processor CP 5412 A2. In a WinCC station, up to four of these modules can be used. However, the system resources available to the PC acting as the WinCC station might result in limitations. Each CP 5412 A2 communication processor can communicate with up to 62 DP slaves. This number only applies if a repeater are used. Otherwise, the general limitation of 32 connected stations to a PROFIBUS network without a repeater applies.

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3.2.4.4 PROFIBUS FMS

Via the communication driver PROFIBUS FMS, a WinCC station can communicate with PLCs that support the FMS protocol. The communication driver PROFIBUS FMS can be used to communicate with devices from different manufacturers. This type of communication can manage a high quantity of data.

Communication PartnerVia the communication driver PROFIBUS FMS, WinCC can communicate with all PLCs supporting the FMS protocol. The following graphic illustrates the possible communication partners.

Communication DataThe communication driver PROFIBUS FMS exclusively supports the communication via the communication processor CP 5412 A2. Per computer, only one module can be used for the FMS communication. In theory, it is possible to communicate with up to 32 FMS devices. However, due to performance reasons you should not communicate with more than 12 FMS devices.

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3.2.4.5 SIMATIC S7 PROTOCOL SUITE

The SIMATIC S7 PROTOCOL SUITE communication driver provides the communication to SIMATIC S7-300 and S7-400 PLCs using various channel units. Among others, two PROFIBUS channel units are available for the communication via the PROFIBUS.

Communication DataThe PROFIBUS channel units support the communication via Hardnet and Softnet modules. A WinCC station can use up to two of these modules. The following table lists the driver software required for the various communication processors. Communication Processor CP 5412 A2 CP 5613 CP 5511 CP 5611 Driver Software PB S7-5412 PB S7-5613 S7-DOS (included in the WinCC delivery scope) S7-DOS (included in the WinCC delivery scope)

The following table lists the number of PLCs that can be addressed by each communication processor used in the WinCC station. The values depend on the PLC type. The enclosed values represent the recommended maximum number. Communication Processor Hardnet Module Softnet Module SIMATIC S7-300 59 (12) 59 (6) SIMATIC S7-400 16 (12) 16 (6)

Communication DataThe communication driver SIMATIC S5 PROFIBUS FDL exclusively supports the communication via the communication processor CP 5412 A2. Per computer, only one module can be used for the FDL communication. In theory, it is possible to communicate with up to 24 SIMATIC S5 stations. However, due to performance reasons you should not communicate with more than 12 SIMATIC S5 stations.

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3.2.5 Communication via Industrial Ethernet

3.2.5.1 Communication ProcessorsTo implement a communication connection to the Industrial Ethernet, the WinCC station must be equipped with a suitable communication processor. In addition, suitable driver software and a communication protocol must be installed for the desired communication. Two types of communication processors are available for WinCC. These are communication processors for the so-called Hardnet and Softnet. The main difference between these two is that Hardnet modules have their own microprocessors to reduce the loads on the computers CPU and Softnet modules do not. Hardnet The entire protocol software runs on the module. The simultaneous operation of two protocols is possible (multi-protocol operation). Module is more powerful than a Softnet module. Softnet The entire protocol software runs on the computers CPU. Only one protocol can be operated at a time (single-protocol operation). Module costs less than a Hardnet module. The following table lists the available communication processors for the system connection to a WinCC station. Communication Processor CP 1413 CP 1613 CP 1411 CP 1511 Configuration ISA Card PCI Card ISA Card PCMCIA Card Type Hardnet Hardnet Softnet Softnet

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3.2.5.2 Communication Drivers

In WinCC, several communication drivers for the communication via Industrial Ethernet are available.

Communication PartnerThe various communication drivers enable the communication to the SIMATIC S5 115U, S5 135U and S5 155U PLCs. They must be equipped with the communication processor CP 1430 TF.

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SIMATIC S5 ETHERNET LAYER 4

The communication driver SIMATIC S5 ETERNET LAYER 4 enables the communication via the SEND/RECEIVE and the WRITE/FETCH interface. The WRITE/FETCH interface permits the active sending of data from the PLC. The communication driver SIMATIC S5 ETERNET LAYER 4 exclusively supports the communication via the communication processor CP 1413. Per computer, up to two modules can be used for the communication. It is possible to communicate with 30 SIMATIC S5 stations per installed communication processor. The following table lists the software components that are required for the implementation of the communication connection of a WinCC station to SIMATIC S5 via the SEND/RECEIVE interface. Name WinCC SIMATIC NET Description Communication Driver SIMATIC S5 ETERNET LAYER 4 Driver Software IE TF-1413

SIMATIC S5 ETHERNET TFThe communication driver SIMATIC S5 ETERNET TF enables the communication via the TF interface (Technological Functions). The communication driver SIMATIC S5 ETHERNET TF exclusively supports the communication via the communication processor CP 1413. Per computer, only one module can be used for the TF communication, which allows you to communicate with up to 30 SIMATIC S5 stations. The following table lists the software components that are required for the implementation of the communication connection of a WinCC station to SIMATIC S5 via the TF interface. Name WinCC SIMATIC NET Description Communication Driver SIMATIC S5 ETERNET TF Driver Software IE TF-1413 Configuration Software COML TF

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3.2.5.4 Communication with the SIMATIC S7

The communication to the SIMATIC S7 is realized via the communication driver SIMATIC S7 PROTOCOL SUITE. It uses various channel units to provide the communication to SIMATIC S7-300 and S7-400 PLCs. ISO Transport ProtocolTwo Industrial Ethernet channel units are available for the communication via the ISO transport protocol ISO-on-TCP Transport ProtocolThe channel unit TCP/IP is available for the communication via the ISO-on-TCP transport protocol. It is recommended to use the ISO transport protocol for networks with small dimensions due to its higher performance. If the communication stretches across more expansive networks connected by routers, the ISO-on-TCP transport protocol should be used.

Communication PartnerThe communication driver SIMATIC S7 PROTOCOL SUITE enables the communication to the SIMATIC S7-300 and S7-400 PLCs. They must be equipped with communication processors supporting either the ISO or ISO-on-TCP transport protocol. The following graphic shows the possible communication partners.

The following table lists the number of PLCs that can be addressed by each communication processor installed in the WinCC station. Module Hardnet Module Softnet Module Connections per Module 30 8

With its two Industrial Ethernet channel units using the ISO transport protocol, the communication driver SIMATIC S7 PROTOCOL SUITE supports the communication with up to two modules. With its TCP/IP channel unit using the ISO-on-TCP transport protocol, it also supports the communication with one module.

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Diagnosis of the Communication Connection

4 Diagnosis of the Communication Connection

The following section is a guideline for troubleshooting and describes procedures for correcting errors. If no communication can be be established between a WinCC station and a PLC after configuring the connection, the biggest obstacle lies in finding the cause of error. The configuration of the connection between computer systems and PLCs can become a very complex task. Errors can creep in at various locations, preventing the connection between communication partners from being established successfully. In this context, the easiest errors are often the hardest ones to find. This section attempts to cover as many problem points as possible. The correction of the found error is then comparably easy.

4.1 Error Detection

An error or the failure of establishing a communication connection is generally first recognized in runtime. If a WinCC picture is switched into runtime and a connection error is present, this fact will be displayed optically. Objects that have been made dynamic with WinCC tags and are not supplied with current process values will be displayed grayed out. Among others, these objects can be I/O fields, sliders, check-boxes or bar displays.

If not all WinCC tags of a connection show an error, this suggests an error source limited to individual WinCC tags. In this case, check the tag addressing, notation and application in the Graphics Designer. If all WinCC tags of a connection show an error, this suggests an error source affecting the entire connection. WinCC has various information sources that can somewhat limit the possible error sources. However, do not expect a pinpoint location of the error.

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4.1.1 WinCC Explorer

The WinCC Explorer includes a separate dialog box for determining the current status of configured connections. This dialog box can only be accessed if the WinCC project is in runtime. If the WinCC project is not in runtime, there are no established connections to the communication partners and therefore their status cannot be monitored. The dialog box for monitoring the current connection status can be accessed from the WinCC Explorer via the Tools Status of Driver Connections menu. The status of all configured connections will be displayed. By selecting the appropriate check-box, a cyclic update in a definable update cycle can be activated.

In the WinCC Explorer, the connection status can also be displayed by pointing the mouse pointer on the connection entry in the right window. The connection status will then be displayed as a Tooltip.

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4.1.2 Channel Diagnosis

To diagnose the communication connections of a WinCC project, the Channel Diagnosis program is available. It can be started via Start Simatic WinCC Channel Diagnosis. This program is only available in English. If the WinCC project is in runtime, the Channels/Connections tab will display all configured connections. In addition, information pertaining to the current communication status of each connection will displayed. The type and quantity of information displayed varies among the different WinCC communication drivers. By default, the displayed information is updated every second.

If there are connection errors, hexadecimal Error Codes will be displayed. These Error Codes aid in localizing error sources more precisely. To do so, you will need an explanation of the error code. By R on the entry of the Error Code and Help, the explanation of the corresponding Error Code will be retrieved from the WinCC Online Help.

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The Configuration tab gives you the option to configure a trace output to a text file. The desired trace depth can be set via the check-boxes in the Flags field. In the Output File Name field, specify the name of the trace file. By default, the trace file is placed in the Diagnosis subfolder of the WinCC installation folder (C:\\Siemens\\WinCC\\Diagnosis). The trace file will receive the extension .TRC and can be opened with any text editor. In the Trace File field, additional trace file settings can be made. The Enable check-box activates the trace output. The settings made must be saved by clicking on the Save button. A warning message will be displayed, informing you that the output of trace information will negatively impact the performance of the communication connection. You should therefore ensure that the trace output is deactivated while plant operations are running. The trace output should only be used during commissioning or for error detection. Before the trace output can occur, runtime must be exited and then started again.

The trace output can only be activated/deactivated if the project is in runtime. To deactivate the trace output, deselect the Enable check-box, store this setting by clicking on the Save button and exit runtime.

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4.1.3 Status Monitoring using the Dynamic Dialog

The status of the individual WinCC tags can be monitored in WinCC runtime. Via the status of such a monitored WinCC tag, ruling out an addressing error, the status of its connection can be inferred. The setup of the status monitoring requires some configuration effort. The configuration of the monitoring is performed in the Graphics Designer. In there, the status monitoring can be configured at any property of an object. For the monitoring, the Text property of a Static Text is a good choice. At this property, a Dynamic Dialog must be configured. A dynamic dialog is created in the Properties tab of the objects properties dialog box. At the desired property, R on the Dynamic column and select Dynamic Dialog from the pop-up menu. This will open the Dynamic Value Ranges dialog box.

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In the Dynamic Value Ranges dialog box, follow these steps: In the Expression/Formula field, specify the tag to be monitored. In the Result of the Expression/Formula field, in the line Other, enter the text Status OK. Activate the Evaluate the Status of the Tag check-box. In the following field, enter a corresponding status text for each existing valid range. Exit the dialog box by clicking on the Apply button. If a different property is used for the status monitoring, corresponding property values must be specified instead of the texts (e.g. colors and such).

If the project is switched to runtime, the just configured object will display one of the entered status texts according to the current status of the tag. If there are no errors, the text Status OK will be displayed.

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4.1.4 Status Monitoring using Global Actions

Another option to configure the status monitoring is to use the internal functions GetTagState and GetTagStateWait. Compared to the GetTag and GetTagWait functions, they not only return the value of a tag, but also its status. This status value can be evaluated and trigger various events. For monitoring a tag, and with it its connection, the creation of a Global Action in the Global Script editor is suggested. This action is triggered by the monitored tag, for example every 2 seconds. The Global Action determines the status value of the monitored tag via the GetTagState function corresponding to the tag type (each tag type has its own function). The status value 0 indicates an error-free communication connection, which can be evaluated in any form.

In the Global Action displayed above a WinCC tag of the Signed 16-Bit Value type is monitored. To determine the status of the tag, the type-specific GetTagSWordState function is used. As the first parameter of this function specify the name of the WinCC tag to be monitored, as the second parameter specify where the determined value is to be written. In the above example, the tag status is further evaluated by the internal tag BINi_E_CONNECTION especially created for this purpose. The value of this tag is set to TRUE in case of an error. The error can then be displayed in various ways. Among other things, this internal tag can be used by Alarm Logging to trigger an alarm or to display a message dialog box.

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4.2 Troubleshooting Guideline

In this section, the communication connection is analyzed step-by-step to determine the responsible error cause of a communication error.

4.2.1 Is the Communication Partner operational?

A basic requirement for successfully establishing a connection is the readiness of the PLC. This mainly means that the PLC must be supplied with power and be in the on status. Additionally, all modules must run without errors. If it is not possible to successfully activate all modules, the checks described in this section can be performed. In general, a successful activation of a module can be assumed, if no error LEDs light up.

Has all necessary Data been loaded?

The configuration of a PLC is primarily done via programming software on a programming device or computer. The data necessary (data blocks, program blocks, etc.) for the operation of a PLC must be loaded into its CPU. Check if all necessary data is present in the CPU. If communication processors are used, it is also necessary to load their data. Check if all necessary data is present in the communication processor as well.

Are the individual Modules operational?

Determine the current module status of the individual components. A simple aid are the LEDs mounted on the modules. Generally, if an attempt to establish a communication connection is made, no error LEDs should light up on the PLC. The illumination of certain error LEDs (e.g. display of an empty buffer battery) may be uncritical for establishing a functional communication connection, however it is recommended to operate the PLC in a completely error-free state. With SIMATIC S7 PLCs, the determination of the module status can be performed comfortably via the STEP7 software. To do this, R on the module entry to be checked and then select Target System Module Status from the pop-up menu to open the Module Status dialog box. In the Status field of the General tab, the current module status and any existing errors are displayed. The Diagnosis Buffer tab contains more detailed information about existing errors and how to correct them.

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Is the Hardware Configuration correct?

For SIMATIC S7 PLCs it is necessary to perform an exact configuration of the hardware. This is made possible by the HW-Config program of the STEP7 software. A hardware catalog for the exact definition of the components used is available. Ensure that the hardware configuration specified in the project corresponds to the actual configuration of the PLC. Individual hardware components are identified by their order number in the hardware catalog. These order numbers are also printed on the hardware components. Check these order numbers for agreement.

In addition, load the hardware configuration into the PLC. Check also if all components of the hardware configuration have been loaded into the PLC.

Are the Communication Processors being synchronized?

With SIMATIC S5 PLCs it is necessary to synchronize any existing communication processors during startup of the CPU. This is performed by the SYNCHRON handling block in the startup blocks of the CPU. As parameters of the SYNCHRON handling block, the interface number of the communication processor SSNR, the desired block size for the data transfer BLGR and the parameterization error byte PAFE are transferred. Below, the call of the SYNCHRON handling block in a startup block of a SIMATIC S5115U is displayed. In this PLC, it is the FB 249.

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4.2.2 Is the Network Connection operational?

Without an operational network connection, a successful communication between a WinCC station and a PLC cannot be established. In this context, the most basic check involves the confirmation that the network connection to each communication partner is working properly (has the network cable been hooked up?).

Checking the Network Connection

There are several options to check a network connection. This means a check to determine if a communication partner can be reached at all via the network connection. For the check of a PROFIBUS or MPI network, the diagnosis of the communication processors used on these networks provides an excellent method. This is done via the program Setting the PG/PC Interface. Select the entry of the corresponding communication processor and click on the Diagnostics button. In the following SIMATIC NET Diagnostics dialog box, all stations accessible via the network connection can be determined by clicking on the Read button.

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Are the correct Network Components being used?

To establish a network connection, the specially provided network components should be used. Otherwise there might be problems with establishing a connection, sporadic connection errors or loss of performance.

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4.2.3 Is the Communication Module in the Computer operational?

To establish a communication connection from a WinCC station to a PLC, an appropriate communication module must be installed on the computer. In most cases, this module is a specifically designed communication processor. In some applications, the use of a regular network card or the computers COM interface can be sufficient. The following explanations mainly deal with the application of communication processors.

Is the Communication Processor operational?

After completing the installation of a communication processor with the Setting the PG/PC Interface program, check if the installation has been successful. Generally, after exiting the Setting the PG/PC Interface program, the user is immediately notified if the installation has been successful or not. Various communication processors provide additional diagnostic capabilities that can be accessed from the Setting the PG/PC Interface program via the Diagnostics button. Clicking on this button will display the Simatic NET Diagnostics dialog box. The diagnosis can be started by clicking on the Test button in the tab displayed by default. The result of the diagnosis will be displayed after that.

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A second option to test a communication processor can be found in its Properties dialog box. This dialog box is accessed by clicking on the Properties button in the Setting the PG/PC Interface program. From the Operating Status tab, the communication processor can be controlled. It can be reset, restarted or a test be performed. The results of the actions performed can be viewed in the lower output field.

Initially, you can try to restart the module. If the restart fails, you will at least receive some information about the cause of error, which will be displayed in the lower output field and error message boxes. Note: While using the Setting the PG/PC Interface program, ensure that already set assignments between access points and the interfaces are not changed unintentionally. This mistake can be made easily due to the structure of the program. To avoid them, the program will point out changed assignments while exiting.

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Determining the Error Source

A source of information for determining the error source is the Sinec2.log file. This file is located in the system folder of Windows NT. In the Windows NT Explorer, this file can be found in the C:\\WinNT\\System32 path and opened from there.

In addition, information can be the gathered from the Event Viewer program. This program is started via Start Programs Administrative Tools (Common) Event Viewer. D on a certain event The Event Viewer program lists all events reported by the system. from the list opens the Event Detail dialog box, which contains more detailed information about the selected event. Via the Previous and Next buttons you can jump to adjacent events.

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Are the assigned Resources still free?

If system resources have been assigned to the communication processor during installation, check if these resources have not already been taken by other devices. You can use the Windows NT Diagnostics program to check this. This program is started via Start Programs Administrative Tools (Common) Windows NT Diagnostics. In the Resources tab of the Windows NT Diagnostics program, the Resources occupied by the various system components are listed.

Compare the already occupied system resources to the ones set for the communication processor. The resources set for the communication processor during installation can be determined with the Setting the PG/PC Interface program as follows: From the Setting the PG/PC Interface program, open the Install/Remove Modules dialog box by clicking on the Install button. In the Install/Remove Modules dialog box, select the desired module entry from the Installed list. Click on the Resources button to display the resources set for the selected communication processor. Compare these values to the already occupied resources.

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If the resources set are already occupied, the settings for the communication processor must be changed to values that are displayed as not occupied by the Windows NT Diagnostics program. Now, a restart of the communication processor with its new values must be performed. This is done from the Properties dialog box of the corresponding communication processor, which is accessed via the Properties button of the Setting the PG/PC Interface program. In the Operating Status tab, click on the Restart button to restart the communication processor. If the restart of the communication processor with its new settings has been successful or not can be gathered from the lower output field.

It is possible that a communication processor might not start even with checked settings. In such a case, experimenting with different settings can lead to success.

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4.2.4 Is the Communication Configuration correct?

To establish a communication connection between a WinCC station and a PLC, certain information about the components involved (WinCC project, communication processors, PLC programs, etc.) must be known for the configuration of each component. This includes information about station addresses, tag names, etc. If one component does not have the correct information, establishing a connection might fail. In this section you will check, if each communication partner has the correct information to successfully establish a connection.

Are the Station Addresses set correctly?

A majority of the communication drivers available in WinCC require the specification of the communication partners station address for the configuration of a connection. Check if the correct station address - configured for the communication partner to be accessed - has been specified. As an example, we will use connections that can be created via the communication driver SIMATIC S7 Protocol Suite. The following graphic illustrates the settings for the channel unit Industrial Ethernet. The address set in the Connection Properties dialog box must agree with the address configured for the communication partner.

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Are the TSAP Values set correctly?

Some communication drivers available in WinCC require the specification of TSAP values for the configuration. These are so-called Service Access Points, which represent the end points of various connections that are used for the execution of certain services. In this context, local and remote parameters are often mentioned. The local parameter concerns the value of the station currently being configured. The remote parameter concerns the value of the station to be accessed by the station currently being configured. Check if the values entered here are the ones that have been configured for the communication partner to be accessed. Ensure that the local and remote parameters have not been reversed. As an example, we will use connections that can be created via the communication driver SIMATIC S5 Ethernet Layer 4. The TSAP values set in the Connection Properties dialog box must agree with the values set for the communication partner. In this example, a comparison of the TSAP values in the hexadecimal format can also be useful.

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Are the correct Rack and Slot Numbers being used?

If a connection is configured via the communication driver SIMATIC S7 Protocol Suite, the exact position of the CPU must be specified except if the channel unit Named Connections is used. In other words, the rack number and slot number of the CPU to be accessed must be specified. Ensure that the values of the communication processor - which are used to establish the network connection - are not entered by mistake in the PLC. Check if the correct rack and slot numbers are used in WinCC and STEP7, and that they agree with the actual values. The following graphic shows the settings for the channel unit PROFIBUS. The values set in the Connection Properties dialog box must agree with the values configured in STEP7.

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Has the correct Access Point been set?

In most cases, the definition of the module to be used for the communication by a certain channel unit of a communication driver is implemented by setting an access point. Check if the access point set here has been correctly assigned to the desired module. As an example, we will use connections that can be created via the communication driver SIMATIC S7 Protocol Suite. The following graphic illustrates the settings for the channel unit Industrial Ethernet. The desired communication module must be assigned to the access point set in the System Parameters dialog box.

In some cases, you have the option of letting WinCC set the access point automatically. In this case, check if WinCC has selected the correct module.

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Is the Addressing of the Tag correct?

If a connection cannot be established to a certain group of WinCC tags created for a connection, the most likely cause is an addressing error of the concerned WinCC tags. The communication partner must be able to map the address configured for a WinCC tag. Check if the addressing has been performed correctly and that the specified addresses exist in the communication partner. As an example, we will use connections that can be created via the communication driver SIMATIC S7 Protocol Suite. The address set in the Address Properties dialog box must be available in the SIMATIC S7.

Another often overlooked error source can be attributed to the configuration of an object in the Graphics Designer that has been made dynamic via a WinCC tag. If the name of this WinCC tag has been entered using the keyboard, typing errors can slip in that can lead you to the erroneous conclusion that a connection error occurred. To avoid such errors, use the tag selection dialog box.

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Are the Network Settings correct?

To establish a working communication connection, some parameters concerning the data transfer must be specified. The type and number of parameters to be set depend on the type of communication network. These parameters must be reported to the various communication partners. Ensure that all communication partners receive identical parameters. As an example, we will use connections that can be created via the PROFIBUS communication driver. Among other things, the transfer rates set for the individual stations must agree. The following graphic shows the settings at a SIMATIC S7 and WinCC station.

If database files are created for the communication, the network settings in them must also be checked for correctness. As examples for the application of database files, we will use communication connections that can be created via the PROFIBUS protocols DP and FMS.

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Is the correct Database File being used?

If a database file is created to realize a connection, it must be accessible by the communication module. The path to this file must be specified. Check if the correct database file has been set and its path and name is correct. As an example, we will use connections that can be created via the communication driver PROFIBUS FMS. In this case, the database file must be assigned to the communication module used. Also make sure that the database file is actually being used. For this, restart the communication module after assigning the database file. A restart can be performed from the modules Operating Status tab in its Properties dialog box.

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4.3 Further Diagnosis

Additional support for localizing and correcting errors is available from the WinCC Hotline, which can be contacted by phone at +49 (911) 895-7000 (Fax -7001). To receive the best support possible, have the following information ready before calling: Information about the operating system used: VersionService Pack Information about the software used: WinCC VersionOption PackagesDriver Software Information about the hardware used:Communication Processor of the PCBus ComponentsPLC Components Trace files created with the Channel Diagnosis program

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4.3.1 Creating Connections via API Functions

This section introduces the concept of creating a connection to a PLC using an API function. To establish a connection via API functions, the communication driver used must first be installed in the WinCC Explorer. The sample illustrates a connection to the SIMATIC S7 via the PROFIBUS channel unit. This new connection contains the connection parameters shown below:

Note: The C-Action used to create the connection is configured at the Mouse Action event of a button. To execute the C-Action, the WinCC picture containing the configured button must be switched into runtime. The action can be tested in any WinCC project. This procedure is only used to demonstrate the application of the corresponding API functions. There are no actual applications, where the creation of a connection from runtime would become necessary.

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C-Action for Creating a Connection

In the first section, the project name is determined. It can be determined while runtime is active via the DMGetRuntimeProject() function. In the next section, the desired values are written to the mcpConnection tag of the MCP_NEWCONNECTION_DATA structure type. Pay special attention to the syntax of the value to be entered in the szSpecific structure element. This structure element defines the connection parameters of the new connection to be created. In the last section, the new connection is created via the GAPICreateNewConnection() function.

Created ConnectionThe following illustration depicts the connection created by the C-Action described above in the WinCC Explorer.